Take Math Shopping!
Percents, estimation, and comparative analysis become more understandable when they are used in-context at the grocery store.
By Ann Whittemore
Teaching opportunities present themselves every day, in nearly any context. Parents and teachers alike are capable of providing engaging, challenging, and enriching moments intended to extend and apply learning to real-life situations. Today we aren’t talking about learning in the classroom, we are heading to the grocery store! This article will be discussing several ways to join the real-life shopping experience with mathematical concepts and reasoning. This scenario can be successful both inside and outside of a classroom setting.
Computing in the Bulk Food Aisle
The grocery store is a fantastic place to apply mathematical concepts taught in school. These suggestions can be implemented by a parent on a family shopping trip, on a class field trip to the store, or modified for use in a classroom setting. Begin by heading over to the bulk foods or produce aisle of your local store. On the way, review or introduce the concept of scale measurement and standard units. Once you get to that section, have younger children practice weighing items and reading the scale. Older kids can look at the price per unit, weigh the items, and mentally compute or estimate the total price. Be sure that they keep the price per pound or unit in mind as they figure out the totals.
Comparing in the Candy Aisle
Price per unit can also be used when comparing prices, values, and cost. Discover this as you move along to the candy aisle. Here, younger children can locate the items that cost the most and least per pound. Ask your shoppers to estimate or calculate how much more one candy item costs than the other. Older learners can compare various candies via weight and price per unit to determine which of two items is a better value. Extend this idea by having kids compare pre-packaged sweets to those found in the bulk candy section.
Calculating Coupon Savings
Coupons and sale items are perfect when you want to practice calculating percentages. Start by ensuring that learners know that a percentage is a part of a whole, just like a decimal, or a fraction. You will probably need to show younger shoppers how percents, fractions, and decimals relate. Bring a calculator to the store to have kids in the middle elementary grades compute the savings of items that are discounted by percentages. Older shoppers can compare the data found at the store to determine if the discounted prices are really the best value.
Cut out grocery store coupons and keep track of how much money is saved with coins. For example, if you save 20 cents on detergent. Ask learners what could be purchased using the savings from the coupon. A pack of gum? How much money could be saved with three, four, or five coupons? How could that money be counted out in coins and bills? What could be purchased with the savings? A magazine? What percentage of the original price is the coupon worth?
Working from the idea that percents, fractions, and decimals are all related because they all describe a part/whole relationship, have kids explore how they know or can show the idea. They can use scales, unit price, and standard measurements to show you that ¼ cup is similar to .25 of a pound and to 25% of a 100. Each measurement shows one fourth of any whole item.
Shapes are everywhere, and the grocery store is no exception. Start this activity by reviewing plane and prismatic shapes. Then have the kids go on a shape scavenger hunt where they check off each shape on their list and write the name of the object next to its shape match. This can be done with colors, letters, words, and numbers. For example, a cereal box is a rectangle, a can of soup is a cylinder, and an orange is a sphere.
Counting at the Check Stand
A lot of math happens at the check stand. Have your child estimate the total price of items in a shopping cart. An easy way to estimate totals is to assign an average price to each item. If you have 10 items and the average price for each item is $2, the total price estimate would be about $20. Using the estimated total, ask your child:
- If I have 10 one dollar bills, how many of these bills will I have to give the clerk?
- If I have a twenty-dollar bill, how much change should I receive?
- If I get coins back, what coins will I get?
- At the checkout counter, what is the actual cost?
- How does this compare to your estimate?
- When you pay for the items, will you get change back?
- Count the change with your child to make sure the change is correct.
Play with the Packaging
Mathematicians call the flat, unfolded designs of three-dimensional shapes nets. Use grocery store packaging to learn about nets. There are three steps to this process. Learner will first predict, then create, and then draw a set of nets. They will discuss what shape they think each of the items will make once they are flattened. Next, they will take the objects apart to see the net. You can also unfold a cardboard box, without showing the child the original box. Ask him to imagine what the original box looked like, and what shape will it be when it is put back together. Have the child trace all the faces of a box, or any other three-dimensional shape by laying every side, top, and bottom on the paper to be traced. After they study their shapes, see if they can draw a net (the unfolded version) of the box. Unfold the box to see how closely the drawn net corresponds to the actual net. What would the net of a pyramid look like? This is a good activity to use when discussing volume, capacity, area, or perimeter.
Adapting for the Classroom
As stated at the beginning of this article, many of the concepts that are used in the context of shopping can also be used in the classroom setting. You don’t have to go nuts and make a classroom store, just bring in the items found at a store. Tangible, concrete items found in a real-life context make classroom math concepts more accessible to kids. Bring in a digital or hanging scale, compare unit price on real packages of candy (empty is fine). Discuss plane and prismatic shapes using real cans and cereal boxes. Put up sale signs around the room. Learners can travel from sign to sign to determine the percentage saved on classroom items in a mock comparison shopping activity. Display store ads and coupons; have students figure out how much money they would save if they bought certain amounts of the sale products. It is also fun and educational to have little ones weigh and measure using real measuring cups. Whatever shopping activities you decide to do, be sure to take the time to have the class discuss how each thing they’ve learned that day can be used in the real world.
Albert Einstein said, “Education is what you remember after you forget everything you’ve learned.” If our kids can’t connect their learning to real life, they are more likely to forget the concepts we have so painstakingly tried to teach them. Parents and teachers can take a real or virtual field trip to the grocery store to ensure that kids connect math concepts with real life. See the ideas below for more ways to bring math to life.
Investigate More Math Ideas:
A wonderful lesson that applies math to shopping skills. The unit revolves around five different activity stations that engage learners in real-world math through receipt calculations, price comparisons, and estimation.
Being a wise shopper definitely involves the use of math skills. It also increases thoughtful choice making, economic understanding, and analytical thinking skills. Teens, work through a series of activities and hands-on demonstrations to discover how useful math really is. They'll practice using percents, ratios, units of measure, and problem solving.
This is a really neat lesson that employs a real-life scenario to help learners practice math problems involving fractions. Use the resource as is, or incorporate it with any of the ideas seen in this article. Learners will double, triple, and half recipes.